Conductive interconnects are used in semiconductor technology. Certain conductive interconnects, sometimes referred to as via interconnects, may be used to electrically couple a metal (or conductive) line of a first metallization level (for example, Metal-1, Metal-2, Metal-3, etc.) to a metal (or conductive) line of another metallization level. Certain conductive interconnects, sometimes referred to as contact interconnects, may be used to provide electrical coupling between portions of a semiconductor substrate and a metal (or conductive) line of the first metallization level (e.g. Metal-1).
While pure copper or copper alloy has been used for the material of the metal lines of the metallization levels, pure tungsten has typically been used for the material of the contact interconnect between the substrate and the first metal level. When pure tungsten is used, a relatively quick increase in contact resistance may result as the diameter of the contact interconnect decreases. A new contact interconnect system is needed.